1. Field of the Invention
The present invention relates to a power supply device utilizing the secondary battery and method of switching the battery mode. Particularly, more than two secondary batteries are employed; one secondary battery is used for supplying the output power to the load, while other secondary battery is used to charge at least one battery at the same time, so that it is possible to improve the energy efficiency.
2. Related Prior Art
Unlike the primary battery, which is disposed after used-up once, generally the secondary battery is rechargeable through the reversible reaction, when it will be discharged.
However, such a secondary battery should be charged again by charging capacity of the battery after a certain time has elapsed, when it is discharged. While the secondary battery is charging, it is impossible to discharging or the efficiency of charging-discharging is significantly diminished. In most cases, more than two secondary batteries are provided for connecting in parallel. Or while the secondary battery is charging by using a separate unit, the other secondary battery is continuously discharging to use.
Furthermore, in case of this secondary battery is continuously used to discharge the normal rated current, it is a common problem that the actual using time of this secondary battery is markedly shortened than the ideal using time set by manufacturer.
As an example, a secondary lead battery converts the chemical energy to the electric energy, which means discharge, and converts the electrical energy to the chemical energy, which means charge, through energy converting cycle function of the battery.
Typically, when the secondary lead battery is in the discharging cycle, the electrode plate reacts with the sulfate (SO4) to produce the water for lowering the specific weight, and combine the sulfate returning to the electrolyte at the charging cycle be heavier specific weight.
That is, the secondary lead battery is composed the electrodes of the lead (Pb) and lead dioxide (PbO2) dipped in the concentrated sulfuric acid solution.Anode: Pb(s)HSO4→PbSO4(s)+H++2e−Cathode: PbO2(s)+HSO4−+3H++2e→PbSO4(s)+2H2OSecondary lead battery: Pb(s)+PbO2(s)+2HSO4−+2H+→2PbSO4(s)+2H2Othe cell reaction takes place as shown above.
The reaction is generated the insoluble PbSO4 and it is deposited on the two electrodes. When the secondary lead battery is discharged, the sulfate is consumed and generated the water. Because the density of the generated water is approximately 70% of the sulfuric acid solution, it is possible to know the charging state of the battery by measuring the density of electrolyte. When the secondary lead battery is charged, the charging reaction of the electrode is reverse as mentioned above.
However, the sulfate deposited on the two electrodes over the long term of the charging/discharging cycles (including self-discharging) won't fall off and stay stuck on there during the charging cycle. This phenomenon is called the sulfate (sulfated).
Such a sulfated phenomenon grows bigger as the secondary lead battery discharge more. This sulfate causes to block the channel of the electrode reaction and act as an insulating function, so that the secondary lead battery are more than slows, Due to the blocking of the chemical and electrical reaction, the voltage, capacity and specific weight of the secondary lead battery is degraded.
Thus, there is a problem that due to the declined efficiency of the secondary lead battery, the battery usable time as fully charged state (discharging time) will be significantly shortened.
In fact, the ordinary (Delco) battery widely used for the automobile, the capacity of a lead battery is 12V, 100 A, which has the power of 1200 W. If the two lead batteries connected in parallel, the total power will be 2400 W. When the two batteries connected in parallel to supply the load 300 W, it will be theoretically used eight hours, but in practice it can be continuous discharged to use only about 1.5 hours. It will be verified in the following <Table 1>.
The <Table 1> shows a configuration of the two lead batteries having output of DC12V, 100 A, which are connected in parallel to load an incandescent lamp of 300 W through 1200 W inverter (model SI-1000A) for continuously discharging. The test result of the inverter voltage and the lead battery voltage were checked for 10 minutes interval.
TABLE 1InverterBatteryLoadoutputInverterConsumedTimeOutputCurrentVoltageCurrentPower(Minute)(V)(A)(V)(A)(KW)Note013.2229.82201.6Start1012.2929.82201.62012.1729.72181.583012.0229.62161.574011.8329.52141.555011.6129.32141.536011.4529.12101.527011.2828.82061.498010.9228.12001.459010.6327.41901.430.49End
As shown in the <Table 1>, when a light of 300 W in the old stall is turned on continuously, such a continuous discharging and depending on the time elapse, the battery output voltage is rapidly dropped. After 1.5 hours (90 minutes) has discharged, the battery output voltage will be 10.64V or less and cannot be discharged no longer due to the weak voltage.
As described above, such a phenomenon is occurred due to the continuous discharging without intermediate charging. As the electrode surface of anode (+) and cathode (−) is coated with the lead sulfate, the reaction rate is diminished and the efficiency of the battery is decreased. Therefore, the only small fraction (0.49 kWh) of the original battery capacity (2.4 kWh) is available.
On the other hand, the number of charging/discharging cycles of the secondary battery has limited. As an example, the lead battery has limitation of 300 cycles. When a battery is charging and discharging approximately once a day, it will have one year life time.
The usable capacity, which is charged through the charging/discharging cycle is diminished over the repetition of charging and discharging cycles. As an example of two Delco 12V 100 A batteries, it can be used 1.5 hours for the first time. It will be 16.6% of the theoretical maximum capacity. But, the third time of charging/discharging cycle, it can be used 1.2 hours (1 hour 12 minutes) and it is available 15% of its original capacity, when it is charged again for sixth time cycle, it can be used only one hour seven minutes, it will be available about 13.9%. Because the percentage of the usable capacity is continuously diminished over the repeated charging/discharging cycles, the usable capacity is nothing after the 300 times cycles.
Additionally, when the lead battery is overload, it causes risk of blow up or damages the equipment. Because the risk of secondary lead battery, it is absolutely prohibited to be loaded by the regulation while it is charging. Usually, the lead battery can be continuously used only about 1.5 hours. Furthermore, it will take about 10 hours to fully charge. So, it is necessary to prepare the extra secondary lead batteries to continuously discharge for a night at the night stall. Also, the secondary lead battery must be fully charged a day before using them. Therefore, it is very inconvenient and uneconomical to prepare the many lead batteries for continuously discharging.
On the other hand, in order to improve the aforementioned problem, more than two batteries are employed for alternately discharging the battery, and supplying the partial discharging power to another battery for using as the charge voltage. This technology has disclosed on the Republic of Korea Patent Application Publication No. 2006-111499.
That is, the conventional technology provides to manage the usage of battery power, the management system and its method. The first battery supplies the power to the second battery for recharging, and supplying to the external load. At the specific time, the switching system and switching method could be switched the duties of the first battery and the second battery. That is, at a specific time, the second battery also provides the power for charging the first battery, while it begins to supply the partial power to the external load. Accordingly, the switching system and the switching method are able to switch the tasks of the first battery and the second battery without interrupting the electric power transmitting to the external load.
As shown in FIG. 1, the first example of the conventional technology shows that the first battery (1) is switched on the exchanging plates (25, 33) and the second battery (2) is switched on the second exchanging plates (26, 34) by setting the charging mode and discharging mode, respectively, through the alternating inverter (45) to supply the power to the load.
Referring to FIG. 1, the first example of the switching system will be described in more detail. The mechanical alternative switch (65) of the generator (100) includes the two batteries (1, 2) as shown in FIG. 1. The electrical generator (100) is used to provide the common domestic light of 2000 to 6000 watts to be extended time in the example uses or capable to provide the other independent environment.
As seen in FIG. 1, the first battery (1) is coupled to an exchanger switch (65) as a power source for providing a direct current. The terminals of the first battery (1) are coupled to the plates (46, 49) onto the bottom plate of first exchanger (34). When the first upper exchanger plate (26) contacts with the lower exchanger plate (34), the direct current is fed to the plates (27, 28) and the inverter (45). The inverter (45) converts the direct current supplied from the battery (1) to the alternating current for supplying to the breaker (37) and the external load (not shown).
On the other hand, in the above example, the AC current is supplied to the converter box (36) from the inverter (45) to operate the gear motor (35). The gear motor (35) drives the upper exchanger plates (25, 26). The gear motor (35) is coupled to the two solenoids (53, 54) to move the plates in each direction. The two solenoids (53, 54) are coupled to the two mechanical switches (51, 52), which switch the moving direction of the two upper exchanger plates (25, 26). The mechanical exchanger switch (65) is activated by a timing sequence. In other words, when the upper exchanger plates (25, 26) move to the rightward by the gear motor (35), the plates activate the switch (51), which operates the upper exchanger plates (25, 26) to move in the opposite direction (left from FIG. 1). The upper exchanger plates (25, 26) are continued to move left until the plate activates the switch (52) to move right. The side sliding velocity of the upper exchanger plates (25, 26) controls the switching frequency from the power supplying mode to the recharging mode of the first battery (1).
When the first upper exchanger plate (26) is moved to leftward as seen in FIG. 1, a direct current is supplied to the plates (27, 28) through the first lower exchanger plate (34) onto the plates (47, 48) from the second battery (2). When the first upper exchanger plate (26) is located on the left, the second battery (2) is supplying the power to the first battery (1), which is in the recharge mode.
That is, as seen in the example of the conventional technology, the management system and method is provided to use the power efficiently, which is provided by the multi-battery. The exchanger switch is set between more than two batteries, so that the single battery is not rapidly consumed. So, one battery starts running out of the power, then, the exchanger switch converts the power source to supply the power from other battery. Another battery is able to supply the recharging current to the weakest battery. The exchanger switch converts the power supply between more than two batteries. The exchanger switch of the power supply system is eventually increasing the battery service life and improves battery efficiency.
However, over the conventional technology of FIG. 1, it is possible theoretically, but there is a fatal problem to use the actual product, for the following reasons. As a result, the domestic and foreign patent applications are all abandoned or withdrawn.
In FIG. 1, the anode (+) of the second battery is connected to the plate No. 8, at the same time, being connected to the plate No. 33, over the terminal No. 9 of the plate No. 13. Further, the cathode (−) of the second battery is connected to the plate No. 25, at the same time being connected to the terminal No. 30 of the plate No. 25. Further, the anode (+) terminal of the first battery is connected to the plate No. 7, and connected to the plate No. 34, at same time, the cathodes (−) terminal of the second battery is connected to the plate No. 33, over the terminal No. 33 of the plate No. 9, at the same time being connected to the plate No. 34.
Accordingly, as an example of the conversion from the second battery (2) to the first battery at the terminal No. 13, the anode (+) terminal of the second battery is contacted momentarily with the cathode (−) terminal of the first battery. Thus, at this point, a strong surge current with a spark is occurred. It causes exploding of the battery. Furthermore, no matter how good conversing point take place, this occurrence is inevitable under the switching operation with the strong current of about 100 A.
On the other hand, the second and third examples of the prior art as shown in FIG. 2 and FIG. 3a, the examples are silent about such a switching terminal and no specific descriptions.
Additionally, the third example of the prior art as seen in FIG. 3b, the flowchart shows the operation of the exchanger switch, and also voltage drop of the battery. The prior art is described the switching conversion, as previously pointed out. However, the prior art did not present any solution for the critical problem. The converter switching for the strong DC current is issued the eventually inherent problems.